Shears vs nibblers

Hand-held Power Metal Shears Comparison of different styles

What is a Hand-Held Powered Metal Shear? These are portable power tools running on electricity or compressed air. They have a reciprocating blade that cuts sheet metal. Most of these units have a rated capacity of 18 ga mild steel (0.040 inch or 1 mm thick). The price generally ranges from $30 to $200 US.

Why would you want to use one? They cut accurately and rapidly along a marked line These are much less expensive than plasma cutters and do not generate sparks. The cut edge only needs to be deburred to be finished. Since they are a power tool, they are easier on your hand than manual snips. They are faster and easier to use than a sabre saw or reciprocating saw. They are much smaller and cheaper than a foot operated shear. They are probably most comparable to a Beverly type shear, but Beverly shears are hand operated and bench mounted. I was first exposed to these shears in a sculpture class that I took in Mexico. I used one every day in class, and bought one as soon as I got home.

There are two types of these shears, the three blade type, and the two blade type, sometimes called throatless.

The three blade type has two fixed blades, with a reciprocating blade in the center. The reciprocating blade cuts out a strip of metal about 1/4 inch (6 mm) wide, which curls up as you advance the tool. This style is particularly good at cutting large panels in two parts. It does not distort the panel, the distortion ends up in the strip instead. However, these units do waste some material (the width of the strip), and cannot cut a tight curve (less than 6 inch radius). I usually use mine to cut straight lines, and find it somewhat difficult to use to cut curved lines. I use a Kett model KD200 shear of this type. This is a good unit, although relatively expensive, around $150. Don't waste your money on the nibbler attachment, it is very difficult to change from the shear to the nibbler.

The two blade or throatless type has one fixed blade and one reciprocating blade. One side of the cut line is pushed up, and the other is pushed down. This type does not waste any material, since it does not produce a kerf strip. It will also cut relatively tight curves, down to 1" or 1.5" (25 to 35 mm) radius. However, it does distort the panels being cut. When used to cut large panels in half, the weight of the panel and the distortion can make it troublesome to advance and control. Sometimes, to facilitate more accurate cuts and to minimize panel distortion, it can be advantageous to rough cut the panel about 1/4 inch (6 mm) outside the cut line, and then go back and cut along the final cut line. This was the style of shear that I used in Mexico, I think it was an old Porter-Cable unit. I own a Harbor Freight shear of this type, $40, cheap and effective, but I had to do some shimming to get the cutting blades parallel.

Another hand power tool that can be used to cut sheet metal is a nibbler. My air nibbler takes little "bites" out of sheet metal, generating hundreds of sharp shards of steel in the shape of a new moon. It cuts out a kerf about 1/4" (6 mm) wide. It can cut tight corners, but is hard to keep going in a straight line. The cut edge is generally very rough. I understand that some nibblers do not gernerate the sharp shards, instead wadding up a strip of crumpled metal. Good for cutting narrow slots and holes or odd shapes in sheet metal, rather than cutting a piece in half. My air nibbler is made by Central Pneumatic, $50 from Enco.

Each unit has it's place, which is why I have one of each type. I use the throatless shear more than the other two put together, but your milage may vary. I hope that you find this useful in terms of choosing what kind of metal shear to purchase.

Richard Ferguson September 9, 2004

D> Hi Folks,